核磁及密度测井耦合的致密砂岩低阻气层饱和度评价方法——以鄂尔多斯盆地临兴神府致密砂岩储层为例

Saturation evaluation method of tight sandstone low resistivity gas reservoir based on the coupling of NMR and density logging:Taking Linxing-Shenfu tight sandstone reservoir in Ordos basin as an example

饱和度评价是油气藏储层评价的核心,直接影响油气储量评价及开发决策。鄂尔多斯盆地临兴神府区块致密砂岩储层低阻气层较发育,依靠电阻率曲线难以准确评价低阻气层饱和度。本文利用储层含气对核磁测井孔隙度和密度孔隙度的影响,通过理论推导,明确了含气饱和度和密度孔隙度与核磁孔隙度之差呈正相关关系,基于密闭取心分析饱和度数据,建立基于核磁及密度测井耦合的致密砂岩低阻气层饱和度模型。含气饱和度计算结果与岩心分析数据吻合较好,使得低阻气层含气饱和度提高16%,为致密气藏储量评估和高效建产奠定基础。

Saturation evaluation is the core of oil and gas reservoir evaluation,which directly affects oil and gas reserve evaluation and development decision-making.Tight sandstone low resistivity gas reservoirs are relatively developed in Linxing-Shenfu block,Ordos basin.It is difficult to accurately evaluate the saturation of low resistivity gas reservoirs by using resistivity curves.Based on the influence of reservoir gas content on NMR logging porosity and density porosity,and through theoretical derivation,it is clear that there is a positive correlation between gas saturation and the difference between density porosity and NMR porosity.Based on the analysis of saturation by closed coring in tight gas reservoir,the saturation model of tight sandstone low resistivity gas reservoir is established based on the coupling of NMR and density logging.The calculated results of gas saturation are in good agreement with the core analysis data,which increases the gas saturation of low resistivity gas reservoir by 16%,and lays a foundation for tight gas reservoir reserve evaluation and high-efficiency production construction.